Recently, higher fuel economy of cars has been strongly demanded because of soaring fuel cost and introduction of environmental regulations. Therefore, higher fuel economy has been demanded of rubber compositions used for producing treads which account for a large portion of a tire among tire components.
One of known methods for improving the fuel economy is a method including reducing the amount of filler such as carbon black. Unfortunately, the reduction in the amount of filler tends to reduce the rubber strength, leading to poor abrasion resistance. For this reason, there are difficulties in achieving high levels of fuel economy and of abrasion resistance at the same time. Meanwhile, in addition to the fuel economy and abrasion resistance, the deterioration resistance is demanded of the rubber composition. Accordingly, a method has been desired in which the fuel economy and abrasion resistance are satisfied at the same time while good deterioration resistance is maintained.
Patent Literature 1 proposes the use of a modified butadiene rubber and the like in order to reduce the rolling resistance. Unfortunately, this proposal still leaves something to be desired from the viewpoint of satisfying the fuel economy and abrasion resistance at the same time while maintaining good deterioration resistance.